Organic Chemistry

Put the remaining substituents on the last available bonds.

Now continue on to Problem 31.

PROBLEM 31

Draw perspective formulas for the following compounds:

a. (S)-3-chloro-1-pentanol c. (2S,3R)-3-methyl-2-pentanol

b. (2R,3R)-2,3-dibromopentane d. (R)-1,2-dibromobutane

PROBLEM 32

For many centuries, the Chinese have used extracts from a group of herbs known as

ephedra to treat asthma. Chemists have been able to isolate a compound from these herbs,

which they named ephedrine, a potent dilator of air passages in the lungs.

a. How many stereoisomers are possible for ephedrine?

b. The stereoisomer shown here is the one that is pharmacologically active. What is the

configuration of each of the asymmetric carbons?

PROBLEM 33

Name the following compounds:

a. c.

b. d.

CH 3

H Cl

C

H C

CH 2 CH 3

CH 3

Br

Cl

HO

OH

C C H

H

CH 3 CH 2 CH 3

Cl Cl

C C NHCH 3

HO

H CH 3

H

CHCHNHCH 3

OH

CH 3

ephedrine

H 3 C

H C C CH^2 CH^3

HO Cl

H

(2S, 3 R)-3-chloro-2-pentanol

H C C

HO Cl

H

S R

208 CHAPTER 5 Stereochemistry